1. Field of the Invention
The present invention is in the field of pulsation dampeners and is more particularly in the field of dampener devices adapted to reduce the amplitude of pulsations generated by multi-piston pumps or the like.
2. The Prior Art
It is known to interpose in a hydraulic system a pulsation dampener which functions to reduce the amplitude of pulses by storing energy when a pulse of high amplitude is encountered and releasing energy when the pressure in the hydraulic system falls to a lower amplitude.
A typical pulsation dampener device may include a pressure vessel divided into two chambers by a bladder, one chamber being filled with gas under high pressure, the other chamber being connected to a conduit carrying the hydraulic fluid medium.
The bladder may typically include a valve member, such as a rigid button which seats on the oil port when the pressures within the gas chamber exceed those in the fluid conduit to prevent the bladder from extruding through the oil port. When the pressures in the liquid exceed the pressures in the gas chamber, the valve member is unseated and the liquid flows into the oil chamber bounded by the bladder.
Energy derived from unseating the valve and further compressing the gas in the gas chamber is thereafter released when the pressures in the liquid conduit fall to a level below the pressure in the gas chamber.
The constant cycle of storing and distributing energy produces a dampening effect on the pulses encountered in the liquid system.
In certain applications wherein positive displacement pumps are employed, whether of the vane, gear or piston type, and particularly of the type employing a high number of pumping elements, the displacement of liquid from each element is very small and the frequency of pulses encountered per unit of time may be very great. When such conditions are encountered, although the cumulative flow of all pumping elements may be high, the displacement of liquid from each element is small. Accordingly, in order properly to dampen the pulses of such devices, it is desirable to provide a dampener which, although having a relatively small gas volume, provides a flow area through the liquid port sufficiently large to handle the total pump flow with minimum amounts of pressure drop across the liquid port.
In the past, pulsation dampeners using button type valves have been satisfactorily employed under such circumstances. However, in the dampening of high frequency pulsations, a button type valve apparatus results in an unpredictable seating of the valve in the port, with consequent damage to the bladder which may become entrapped between the button and the seat.
To reduce the likelihood of damage to the bladder, resort has been made to poppet type valve assemblies which provide a guiding function. However, such devices do not provide the desired high flow-through area necessary where high frequency pulses are encountered and have the further disadvantage of adding materially to the forces which must be overcome before the liquid in the conduit is communicated to the interior of the pressure vessel.